Thermostatically controlled immersion electric heater



W. M. SAGE May 21, 1940.

Filed Oct. 30, 1937 WarreflMSa e;

mantra May 21, 1940' THERMOSTATICALLY CONTRQLLED IMLIERSION ELECTRICHEATER Warren M. Sage, Toronto, Ontario, @anacla Application October 30,1937, Serial Pi 121L876 3 Claims.

The principal objects of this invention are to provide an ersion type ofelectric heating device which may be easily and quickly adjusted to heatthe fluid in which it is immersed, and elicctively maintain thetemperature ofsuch fluid at any desired degree of heat;

A i'urther and important object is to devise a structure which may bemanufactured at low cost, so as to render it readily available to thepublic,

n and which will be thoroughly dependable and tree from danger to theuser either from shock or fire hazard.

The principal feature of the invention constats in the novel arrangementof an electric heating element within a chamber at the sealed end oi ametm tube and a thermostatic device within an adjacent chamber in saidtube separated irom the heating chamber by a heat insulating wall, sothat the thermostat is affected 2o principally by the temperature of theliquid surrounding the tube.

In the accompanying drawing, Figure 1 is a longitudinal sectionalelevation of a heater constructed in accord with this invention.

Figure 2 is an enlarged cross sectional detail through the heater on theline 22 of Figure 1.

Figure 3 is a longitudinal sectional elevation of a portion of a heatershowing a modified form oi thermostat adjustment.

Figure 4 is a detail view similar to Figure 3 showing another form ofthermostat adjustment.

lit

Figure 5 is a cross section of the device shown in Figure 4 taken on theline 5-5 of Figure 4.

Figure 6 is a miniature elevation of a modified form of heater.

Figure 7 is a view similar to Figure 3 showing a form of thermostatadjustment as applied to the form oi. heater shown in Figure 6.

Figure 8 is an elevation showing one manner 40 of using the heater.

Tubular immersion heaters with thermostatic controls have been devisedin various forms, but most of these are controlled by the directinfluence of the heater.

The present invention consists in providing a tube 1! having the end 2thereof sealed. A block of heat and electrical insulating material 3,preferably of porcelain fits snugly within the interior of the tube andis spaced intermediate of the length thereof.

A porcelain tube 4 forming part of the block 3 or mounted in a recess inone end thereof supports the electric heating element 5 within thechamber 8 at the sealed end of the metal tube.

6, and the terminals extend through suitable holes in the block to thechamber i.

A plate 8 which may be of metal or an electric insulating material suchas Bakelite is secured to the bloclr. t and extends lengthwise centrallyof the tube 8, and in the form shown in Figure i, it supports aninsulated terminal 9 adjacent to the block.

A bi=metallic thermostatic arm in having a spiral end it is mounted on astud l2 rotatably 1d mounted in an insulated bearing l3 in the plate 3,and its contact end it co-operates with the terminal ii.

An electric conductor I5 is electrically connected with the stud l2supporting the bi-metallic i5 arm ill and a conductor It extendsdirectly through to one end of the heater coil while the other end ofthe heater coil is connected by conductor 55' to terminal 9.

A suitable form of condenser I1 is coupled be tween the terminals 9 andM on the opposite side of the plate 8 to the thermostat to eliminatesparking of the contacts.

An arm it is secured to the stud I2 andv has a pointer IQ of insulatingmaterial extending to a scale 20 mounted on the plate and by means ofwhich the thermostat is adusted to open at predetermined temperatures ofthe fluid to be heated.

A screw cap 2| seals the end of the tube, and through this the electricconduits 22 and 23 extend from a suitable contact plug.

It will be understood that when this tube is inserted into a receptacle24 containing a fluid to be heated. the tube will be immersed to a pointwell above the porcelain block, so that the fluid will absorb heatgenerated in the tube and the temperature within the thermostat chamber'1 will be the mean temperature of the heat conducted upwardly by thetube l above the heating 4 0 chamber 6 and the temperature of the fluidsurrounding same.

It will thus be readily appreciated that the temperature afiecting thethermostat will be practically the temperature of the surroundingliquid, and the scale for the regulator can be readily calibrated toenable the pointer to be set at a figure representing the heat, which itis desired to be maintained in the fluid.

The simplicity and reliability of the device thus described will bereadily appreciated.

Many different forms of thermostatic design and control may besubstituted for that shown, and though I have shownseveral modifiedforms,

these are merely shown by way of example, the general arrangement ofheater and thermostat being the same.

In the form shown in Figure 3 the stud 12 of the thermostat arm l has anarm 25 connected to a rod 26 into which a screw 21 mounted in an orificein the tube cap is threaded. The rod extends through a suitable stuflingbox 28, and has an indicator knob on the top and the rod is preferablyheld under the tension of a spring 29.

In Figures 4 and the thermostat Him is of the corrugated or bowed typeand its spacing from the fixed terminal for temperature adjustment iseffected by turning the disc 30 threaded on the stud Hm.

Again in Figures 6 and 7 the tube is preferably square, so that it willbe flat on the bottom of a dish containing fluid to be heated. Thetubeis provided with a ferrule 31 in the side wall closed by a sealingcap 32 through which access is obtained to an adjusting screw 33 bywhich the thermostat is regulated.

What I claim as my invention is:

1. In an electric heater of the tubular immersion type having anelectric heating unit and a thermostatic control unit, a block ofinsulating material rigidly connected with and mounting said electricheater and control unit in segregated relation respectively on oppositeends thereof, the whole forming a rigid assembly insertable into orremovable as a unit from the tubular portion of the heater.

2. In a tubular immersion heater of the type having a resistance heaterand a thermostatic switch control, means forming a rigid mountingconnection between said heater and switch control including a porcelainblock interposed bodily between the switch and heater and having theresistance heater directly mounted thereon and supported thereby inspaced relation to the tubular member.

3. Means as claimed in claim 2 in which said porcelain block is providedwith an axial porcelain extension of smaller" diameter than the block onwhich the element of the resistance heater is wound and is supportedthereby centrally of the tubular member in rigid association with theblock and insertable and removable therewith as a rigid unit. I

4. Means as claimed in claim 2 in which said mounting means includes apartition member rigidly secured to one end of said refractory block andextending longitudinally of the tubular member and completely from sideto side thereof in diametrical relation dividing the tubular member intotwo compartments and engaging the tubular wall at opposite sides inbracing and positioning contact.

5. Means as claimed in claim 2 in which said mounting means includes apartition member rigidly secured to one end of said refractory blockandextending longitudinally of the tubular member and completely fromside to side thereof in diametrical relation dividing the tubular memberinto two compartments and engaging the tubular wall at opposite sides inbracing and positioning contact, said partition being formed solely of astrip of insulating material and the switch member being mounted thereonto operate in one of said compartments on one side of the insulatingpartition and a condenser bridging the switch contacts being supportedby the partition on the opposite side thereof within the other of saidcompartments.

6. Means as claimed in claim 2 in which said mounting means includes apartition member rigidly secured to one end of said refractory block andextending longitudinally of the tubular member and completely from sideto side thereof in diametrical relation dividing the tubular member intotwo compartments and engaging the tubular wall at opposite sides inbracing and positioning. contact, a pointer enclosed within the tubularmember and connected with the thermostatic member for adjustmenttherewith, and a scale carried by said partition member with which saidpointer co-operates.

'7. In an electric heater of the tubular immension type having anelectric heating unit and thermostatic control unit enclosed therein,means for adjusting said thermostat including an adjusting screwaccessible through an opening in the wall of the tubular enclosingelement, and means forming a removable sealed closure about the wallopening to permit the tubular member to be submerged ina body of liquidto a depth such that the liquid surrounds the said wall opening withoutleakage thereinto.

8. Means as claimed in claim 7 in which said wall opening is providedwith a threaded tubular extension through which the adjusting meanswithin the tubular member is accessible, and a cap member threaded onsaid tubular extension and sealing the entrance thereto.

WARREN M. SAGE.

